not self-adhesive, but even falling

I had bought this cable channels, because I do not have to screw. Unfortunately they have not fulfilled this expectation. After they now hang about 2 months, they are all suddenly dropped almost simultaneously. It is not the first time that I have been working with such self-adhesive material, so I know how to deal with it, so that it sticks well, and I also know that there are quite adhesive surfaces that actually stick. These do not, unfortunately.
So I had to pick up the tools but now - I would also equal the cheaper channels can buy at the screws. Very disappointing.